1. Field of the Invention
This invention relates a driving control circuit, a driving control method and an electronic equipment provided with the driving control circuit which are preferable for driving an electromagnetic motor or the like.
2. Description of the Prior Art
As a driving control circuit for driving an actuator such as an electromagnetic motor or the like, it is well known that there is provided a circuit to cause the actuator to be connected to the collector terminal of a transistor so as to apply a control voltage to the base terminal of the transistor.
In FIG. 7 is shown one example of a circuit diagram of this type of prior art driving control circuit. In FIG. 7, reference numeral 101 denotes a control arithmetic section, 102 a driving circuit, 103 an actuator section, and 104 a position sensing unit for use in sensing a driven position of a rotor magnet 103-2 of the actuator section 103.
In addition, to the control arithmetic section 101 are inputted a certain target value to cause the actuator section 103 to be rotationally controlled up to a desired position and a controlling amount signal outputted from a position sensing unit 104. Within the control arithmetic section 101, the target value is inputted to a non-inverting input terminal of an OP amplifier 101-5 through an impedance element (Z3)101-3, and the controlling amount signal is inputted to an inverting input terminal of the OP amplifier 101-5 through an impedance element (Z1)101-1. An impedance element (Z4)101-4 is connected between a non-inverting input terminal of the OP amplifier 101-5 and the ground and further a negative feed-back impedance element (Z2)101-2 is connected between the non-inverting input terminal and an output terminal of the OP amplifier 101-5. These impedance elements are comprised of either a single resistor or a combination of a resistor and a capacitor.
Operation of the driving control circuit constructed as described above will be described as follows, wherein a negative feed-back impedance element 101-2 is connected to the OP amplifier 101-5, resulting in that such an output signal as one in which a signal inputted to a non-inverting input terminal and a signal inputted to a non-inverting input terminal may become the same value is outputted. In this case, a target value is applied to a non-inverting input terminal of the OP amplifier 101-5, a voltage is divided by the impedance element 101-3 and the impedance element 101-4 and applied and a control amount signal obtained from the position sensing unit 104 is inputted to the inverting input terminal through the impedance element 101-1, so that an error signal in which a controlling amount signal is coincided with a target value is outputted from the OP amplifier 101-5.
The driving circuit 102 is driven after this error signal is supplied and an error signal is applied to the base terminal of the transistor 102-2 in the driving circuit 102 and then an emitter current corresponding to that level starts to flow.
As a result, the emitter current at the transistor 102-2 is applied as a current amount corresponding to a difference between the target value signal and a controlling amount, and then the rotor magnet 103-2 is rotationally driven in response to this emitter current amount.
Accordingly, the rotor magnet 103-2 of the actuator section 103 is rotated up to a predetermined rotational angle corresponding to the target value. In addition, a rotating amount of this rotor magnet 103-2 is detected by the position sensing unit 104, fed back to the control arithmetic circuit 101 and the driving circuit 102 becomes to be driven by the error signal until the rotor magnet 103-2 reaches up to the position of the target value.
In the aforesaid prior art driving control circuit, a base-biasing voltage of the transistor 102-2 in the driving circuit 102 is applied as an error voltage and the emitter current is controlled in an analogous manner, resulting in that the transistor 102-2 is operated in a non-saturated region. Accordingly, at the transistor 102-2, an electrical power in which the emitter current (collector current) and a collector-emitter voltage are multiplied to each other is consumed. Since this electrical power is a useless electrical power consumed as heat, the prior art driving control circuit had a problem that an electrical power efficiency in the driving circuit 102 showed a low value.
In view of the foregoing, it is an object of the present invention to provide a driving control circuit, a driving control method and an electronic equipment capable of improving an electrical power efficiency of the driving circuit.